Subtract 21/45 from 12/7, Solve 1 5/7

Subtract 21/45 from 12/7

1^st number: 1 5/7, 2^nd number: 21/45

12/7 - 21/45 is 131/105.

Find the least common denominator or LCM of the two denominators:
LCM of 7 and 45 is 315

Next, find the equivalent fraction of both fractional numbers with denominator 315
For the 1st fraction, since 7 × 45 = 315,
12/7 = 12 × 45/7 × 45 = 540/315
Likewise, for the 2nd fraction, since 45 × 7 = 315,
21/45 = 21 × 7/45 × 7 = 147/315
Subtract the two like fractions:
540/315 - 147/315 = 540 - 147/315 = 393/315
After reducing the fraction, the answer is 131/105
In mixed form: 126/105

MathStep (Works offline)

Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad